President Trump‘s daughter-in-law opened the letter addressed to Donald Trump Jr. about 10 a.m. at the couple’s Manhattan apartment. It’s unclear what the “white powder” was.

Vanessa Trump was taken to the hospital as a precaution, police said. Two other people were reportedly also taken to the hospital, according to ABC7NY. The couple has five children, though it was not clear if any were home at the time of the incident.

Police and Secret Service are investigating the incident.

Trump Jr. is the eldest son of the president. He married Vanessa in 2005.